The invention disclosed herein pertains to display devices such as are commonly known as neon signs and, in particular, to resilient supports for the gas filled glass tubing used in such signs.
Neon signs comprise glass tubes which are bent into various configurations and have electrodes sealed into their opposite ends. The color of the light which is emitted when a high electric potential is applied across the electrodes depends on the particular inert gas with which the tube is filled. Argon, krypton and neon are the most commonly used gases, but for the sake of brevity, all light emitting gas filled tubes to which the new tube support is applicable will be called neon tubes herein.
Neon signs customarily comprise frames or panels on which the configured gas filled glass tube is supported by means of standoffs or insulating supports. These supports are designed to hold the neon tubing in a fixed position and also to act as shock absorbers which function to allow the neon filled glass tubing to flex a little rather than fracture when the sign is subjected to a distorting or a vibrational force.
Neon signs are typically comprised of a base on which the tube supports are mounted in a pattern that conforms to the configuration of the neon tube. Commonly used prior art supports are comprised of a cylindrical body, usually of metal, which has an axial bore and contains a coaxial metal helical coil spring having one end engaged with the body in the nominally bottom end of the bore. A stem enters the bore coaxially with the spring. One end of the stem connects with the spring like a spring biased plunger and the other end of the stem extends from the cylindrical body. This end of the stem may terminate in an integral c-shaped element which can engage the neon tube for supporting it effectively on the spring. Sometimes there are notches on the part of the stem which extends from the cylindrical body for facilitating using a tie wire to positively secure the neon tube to the stem.
Commercially available neon tube supports are more costly than one might assume after inspecting them. Much of the costs results from having to make the parts, including the cylindrical body, the stem and spring separately and then undertake at least a two step assembly operation before a tube support is ready for use.
Designers and users of tube supports have striven to reduce costs with various implementations of the basic tube support outlined above. None of the designs are optimized for high production rates and lowest cost. The economic benefit that could be achieved with an optimized design is substantial. There are major neon sign manufacturers which use at least two hundred thousand tube supports per week every week of the year. The annual savings that can result from reducing the cost or price of the tube supports by one cent (U.S.) can amount to over $200,000 (U.S.) per year for such manufacturer. The new tube support disclosed herein saves substantially more than one cent per support as compared with the lowest cost tube support of which applicants are aware.
Initially, applicants perceived that an all plastic tube support, including the spring, could be a very low cost design. Conventional molds and molding practices were tried. A metal pin was used to core out the helical spring. It turned out that, since the core pin is trapped within the spring, it acquired heat from the hot molten plastic each time a mold or cast was made but it could not give up enough heat between molding cycles to prevent prolonging the amount of time that the molding material remained fluid due to heat derived from the core pin. This resulted in less than optimum productivity. Applicants then conceived a molding method which provides for making all parts of the support of plastic, eliminating the need for a core pin, making a plastic spring practical, and achieving high production rates.